why you don't use TIM1 in PWM mode ?
You can run timer counter in 1ms (as example) and channel 1 in pwm: ARR =
3000 and CCR1 = 2000 and you will get your signal without caring about
it in software. Your CPU will be loaded-off.

Actually, i'm testing on a pre-designed pcb circuit, so my timer 1 does not connect to any LEDs, only timer3 does. That's why i'm using timer3.

Understands that setting CCR to the ratio of the ARR can get the desired outcome... As i need to show that I can use PWM mode to make the LED glow and off.

Currently I manage to get the effect on and going.

Thanks a lot.

Hi toh.seng_huat,

why you don't use TIM1 in PWM mode ?
You can run timer counter in 1ms (as example) and channel 1 in pwm: ARR = 3000 and CCR1 = 2000 and you will get your signal without caring about it in software. Your CPU will be loaded-off.